1. Field of the Invention
The present invention relates to a method and system for determining the connection states of straight short vectors representing a figure.
2. Description of the Related Art
To acquire figures and outlines of characters in the field of computer graphics, computer aided design (CAD) and generation of outline fonts, a method has been used which fits, for example, a Bezier curve to a plurality of straight short vectors approximately representing an original figure.
In this method, when straight short vectors are given to represent the original figure having straight line segments and curve segments, the curve fitting is performed for each of the straight short vectors. For example, if the original figure is reconstructed with straight short vectors as shown in FIG. 1, a figure as shown in FIG. 2 will be obtained because a curve is fit to each of the straight short vectors. That is, the figure resulting from the curve fitting to a straight line segment or a corner point may differ from the original figure. In order to obtain a figure which more closely approximates the original figure, therefore, it is required to fit the curve only to curve segments of straight short vectors approximately representing the original figure.
To fit the curve only to curve segments, a point (corner point) at which the gradient in an original figure is discontinuous is detected on the basis of straight short vectors. That is, when an angle formed by two adjoining straight short vectors is less than a reference angle .theta.ref, it is determined that the connecting point of the adjoining short vectors is a corner point. It thus becomes easy to distinguish between straight line segments and curve segments.
In some cases, however, a corner point cannot accurately be detected from straight short vectors representing the original figure. For example, when an angle .theta.2 at the connection point of curve segments of straight short vectors (see FIG. 4) representing the original figure shown in FIG. 3 is equal to the angle .theta.1 at the corner point of the original figure, both of the connecting points may be determined as being corner points or points other than corner points, depending on the reference angle .theta.ref.
As can be seen from the above, by the method in which the connecting point of two straight short vectors is determined as being a corner point when an angle .theta. formed by the two straight short vectors is less than the reference angle .theta.ref, the corner point cannot accurately be detected. Therefore, it is not easy to distinguish straight line segments and curve segments from given straight short vectors.
In view of the above, a method for determining the connecting states of connecting points is desired to distinguish straight line segments and curve segments from given straight short vectors easily.